Celtic myth and lore is full of strange creatures. Some that don't quite have an analogue anywhere else. The Fachan is one such creature. Their might be similar creatures in other myths (I bet the Japanese or the myths of India have something like this) but none I can recall off the top of my head. This book gives us the background on the Fachan, 3.x style monster stats and some ideas to use it in your games. There is also a Fachan NPC and some notes on using the beastie as a character race. All in all not bad, and then when you consider the price then it is great.